1. Field of the Invention
This invention generally relates to medical devices and, more specifically, to kink-resistant surgical access devices adapted to introduce surgical instrumentation into body conduits and methods of making same.
2. Discussion of Related Art
Surgical access devices such as sheaths and catheters have long been used to access body conduits. Surgical access devices typically include an access sheath and an obturator or dilator inserted therethrough to facilitate introduction of the access sheath into a body conduit. Once the sheath is positioned inside the body conduit, the obturator is removed leaving a working channel for fluid delivery, fluid recovery, implant delivery and, on many occasions, they provide an access pathway for an instrument such as an endoscope. It follows that such a sheath needs to be as durable and flexible as possible. A serious problem arises when an access sheath is bent or twisted causing the sheath to kink. A kinked sheath is useless because it cannot communicate and because it will not allow the passage of an instrument such as a guidewire or an endoscope. In addition, a kinked sheath may allow an endoscope or other device to puncture the wall. This could present a danger to the body conduit into which the sheath has been inserted. Consequently, the kinked sheath must be removed and/or replaced. As such, there has been a need in the art for an access sheath having a kink-resistant construction. U.S. Pat. No. 5,380,304 (the '304 patent) and U.S. Pat. No. 5,700,253 (the '253 patent) attempt to address the kinking problem by disclosing a sheath comprising an inner tube, a flat wire coil compression fitted around the inner tube, and an outer tube connected to the inner tube through the spacings between the wire coil. Specifically, the outer surface of the inner tube is chemically etched to form a rough outer surface to which the outer tube is mechanically connected using a heat shrinking and formation process. There is still a need, however, for alternative and improved methods of manufacturing kink-resistant sheaths for use in body conduits that are effective, cost-efficient and provide good yields.
Furthermore, the present access sheath has been provided in the form of an elongate tube that has tended to migrate distally and, in some cases, have disappeared beneath the body conduit such as the urethral meatus. U.S. patent application Ser. No. 09/882,630 (Publication No. 2002/0038115 A1), which is hereby incorporated by reference, addresses this problem by providing an access sheath having an enlargement at the proximal end to prevent migration and to facilitate the insertion and removal of instrumentation. In particular, the sheath includes a handle structure at the proximal end that is sized and shaped to accommodate engagement by a user's hand disposed in its natural position with the palm facing the user. Specifically, the handle has a funnel structure that facilitates the introduction of instrumentation into the working channel of the sheath. As a result, the sheath is positioned in a relatively stationary orientation during the insertion and removal of instrumentation. However, these sheaths with handle structures at the proximal ends have large openings and, therefore, it would be desirable to provide a mechanism such as a cap that releasably attaches to the handle structure to further facilitate use with the surgical instruments.